The Sneca III is a very poor aircraft loadwise to utilise for Public Transport Flying. I used to fly the last model off the production line which was dual instrumented and had radar. Half tanks and 4 adults took you over MTOW. And apart from reliance on guages, how did you know what fuel level you really had.
I would suggest to anyone hiring from any organisation that you have to bear in mind that if you are in the left hand seat, the responsibility for the safe conduct of the flight lies with you. If too many constraints are placed on you, find a plane from elsewhere.
In reading the AAIB report and both threads, the thing that amazes me was this organisation's desire to have the plane returned with minimum fuel so not to cock up the potential for a subsequent charter. Obviously the kind of aerial work carried out is unknown, but who would be flying the aircraft next that would not rquire at least an hours fuel plus some safety margin
Therefore to quibble about it suggests that their weight & balance / loadsheets may perhaps have been "marginal"! (for want of a more cynical way of putting it).
I learned to fly in the U.K. but recall validating my licence in Australia many moons ago and on x-country flight planning out there fuel calcs were a high priority. If memory serves me right, there was no mention of taking taxiing fuel quantities into account - only airborne consumption - WHY?